l-Cysteine modified silver nanoparticles-based colorimetric sensing for the sensitive determination of Hg2+ in aqueous solutions.

A simple and sensitive colorimetric sensing method was constructed for detection of Hg2+ in aqueous solutions and based on silver nanoparticles functionalized with l-cysteine (l-Cys-Ag NPs). In this method, adenosine triphosphate (ATP) induced aggregation of l-Cys-Ag NPs. Simultaneously, the solution colour changed from bright yellow to brown. In the presence of Hg2+ , Hg2+ chelated ATP to form a complex and reduce the degree of aggregation of l-Cys-Ag NPs and was accompanied by a colour change from brown to bright yellow. The changing values of absorbance at 390 nm were linearly correlated with concentration of Hg2+ over the 4.00 × 10-8 to 1.04 × 10-6 mol·L-1 range, with a detection limit of 8 nM. This method was used successfully for detection of Hg2+ in real water samples and performed good selectivity and sensitivity. The recovery range was 91.5-109.1%, indicating that the method has vast application potential for determination of Hg2+ in the environment.